1. After the flower has bloomed and starts to die back, cut off the head.
2. Allow these to dry. I use a tray for at least a week. Sometimes I wait until longer keeping them in a shed or somewhere where they will not be eaten until I have time to get to them, even if that is the fall when the weather is cooler.
3. Remove any leaves or other chaff. Push out the seeds into a tray.
4. Further remove chaff by tossing the tray slightly up in a slight breeze.
5. If all of the chaff is gone then you can put in a jar or an envelope and I put mine in the freezer. Don't forget to label. If chaff still remains I pick out the seeds and put them in the jar individually which takes considerably longer. I have not mastered the chaff removal process.
Done! Plant next spring and repeat.